Printing an image onto a print medium such as paper for consumer and industrial use is dominated generally by laser technology and ink jet technology. Ink jet technology has become more common as ink jet printing resolution and print quality has increased. Ink jet printers typically use either thermal ink jet technology or piezoelectric technology. Even though they are more expensive to manufacture than thermal ink jets, piezoelectric ink jets are generally favored as they can use a wider variety of inks and eliminate problems with kogation.
Piezoelectric ink jet printheads typically include a flexible diaphragm manufactured from, for example, stainless steel. Piezoelectric ink jet printheads can also include an array of piezoelectric transducers (i.e., actuators) attached to the diaphragm. Other printhead structures can include one or more laser-patterned dielectric standoff layers and a flexible printed circuit (flex circuit) or printed circuit board (PCB) electrically coupled with each transducer. A printhead can further include a body plate, an inlet/outlet plate, and an aperture plate, each of which can be manufactured from stainless steel. The aperture plate includes a plurality of nozzles (i.e., one or more openings, apertures, or jets) through which ink is dispensed during printing. The number of nozzles per unit area generally determines the printer resolution, with higher resolution devices having more apertures within a given area. As printer resolution increases, the size of the nozzles and the quantity of ink in each ink drop dispensed onto a print medium decreases.
During use of a piezoelectric printhead, a voltage is applied to a piezoelectric transducer, typically through electrical connection with a flex circuit electrode electrically coupled to a voltage source, which causes the piezoelectric transducer to bend or deflect, resulting in a flexing of the diaphragm. Diaphragm flexing by the piezoelectric transducer increases pressure within an ink chamber and expels a quantity of ink from the chamber through a particular nozzle in the aperture plate. As the diaphragm returns to its relaxed (unflexed) position, it reduces pressure within the chamber and draws ink into the chamber from a main ink reservoir through an opening to replace the expelled ink.
During printhead manufacture, contaminants can be introduced into the printhead. These contaminants can be transported to the nozzle during printing where they can block the flow of ink through the nozzle and reduce print quality. To filter contaminants in the printhead a stainless steel particulate filter or “rock screen” can be used.
Printhead structures which can improve print quality and reduce printhead costs would be desirable.